DC-to-DC converters change DC electrical power from one voltage level to another. Typically, a DC-to-DC converter converts a supply voltage level of DC power to an output voltage level. For example, 1.5 volts DC from a battery can be stepped up to a higher voltage to operate electronic circuitry. DC-to-DC converters also may be used to provide ground isolation, power bus regulation, etc.
There are various types of DC-to-DC converters including buck converters, boost converters, and buck-boost converters. The buck converters and the boost converters step the input voltage down and up, respectively, and a buck-boost converter can either step the input voltage up or down.
Typically, DC-to-DC converters rely on the switching between a first stage where energy is being received from a source and a second stage where energy is delivered to a load. The switching can be done using transistors such as MOSFETs or IGBETs as high frequency switches. One drawback to the use of transistor switching in high switching frequency applications is that the switching of the transistor switches from an on to an off state can result in the production of noise as manifested by high-frequency energy that can be transmitted by electromagnetic induction to other nearby equipment, causing interference and power loss. This problem has lead to the development of lossless, soft switching. One version of a converter having high efficiency and lossless switching is described in U.S. Pat. No. 6,388,896. The converter disclosed in U.S. Pat. No. 6,388,896 includes a lossless DC-to-DC converter, thus enabling a high switching frequency with reduction of converter size and weight. While a converter with lossless switching is described in the U.S. Pat. No. 6,388,896, there is not disclosure of an appropriate control circuit to control the switching of the converter.
Accordingly, it is desirable to provide a control circuit for a DC-to-DC power converter having lossless or near lossless, soft switching. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.